Means for mounting the presser foot on sewing machines



May 23, 1961 R. REEBER ETAL MEANS FOR MOUNTING THE PRESSER FOOT ONSEWING MACHINES 3 Sheets-Sheet 1 Filed Aug.

III

6 W H mp M N Gu'hfher MALL Ger/10rd 5EEW4LD Rubi SC/WWT/l/M May 23, 1961R. REEBER ET AL MEANS FOR MOUNTING THE PRESSER FOOT ON SEWING MACHINES 3Sheets-Sheet 2 Filed Aug. 18, 1958 F/Gd /NVENI'0A 5 y 1961 R. REEBER ETAL 2,985,127

MEANS FOR MOUNTING THE PRESSER FOOT ON SEWING MACHINES Filed Aug. 18,1958 3 Sheets-Sheet 3 FIG. 7

10a f 7/0 jg 07 25 /04 w ff? INVL-NTOQS Rudolf PL'FBE/Q Gin/her MALLGerhard 5FW4LD United States Patent MEANS FOR MOUNTING THE PRESSER FOOTN SEWING MACHINES Rudolf Reeber, Gunther Mall, Gerhard Seewald, and RubiSchiinthaler, all of Kaiserslautern, Pfalz, Germany, assignors to G. M.Pfatf A.G., Kaiserslautern, Pfalz, Germany Filed Aug. 18, 1958, Ser. No.755,519

Claims priority, application Germany Aug. 24, 1957 '7 Claims. (Cl.112-440) This invention relates to sewing machines and more particularlyto means for mounting the presser foot upon the presser bar of a sewingmachine.

In most sewing machines the presser foot is secured to the presser barby means of a clamping connection. If a knurled clamping screw is usedfor this purpose the connection between the presser foot and the presserbar can be established and released without a screw driver beingrequired. However, the strength of the fingers of the seamstress is notsufiicient in all cases for securing the presser foot safely without theaid of a tool.

It is an object of the invention to provide means for mounting anddismounting the presser foot of a sewing machine conveniently andsafely. It is a further object of the invention to provide asatisfactory connection between the mounting parts of a presser footwhere the guiding surfaces are not too accurately machined.

The invention is based on known arrangements where the presser foot issecured to the presser bar by means of a special mounting which isreadily releasable. In accordance with the invention the support memberis provided with a rotation opposing cylindrical guide slot extending inthe direction of sewing and spring biased latch means, which areself-locking by virtue of wedge action, for a guide member on the shankof the presser foot formed to correspond to and slidingly received inthe guide slot in its position which is determined by an abutment. Theexpression cylindrical guide slot is intended to mean a guiding surfacewhich comprises parallel lines. The latching means is considered to beself-locking by virtue of the fact that frictional forces are developedunder a load which are greater than the load and oppose the same.

For such a mounting, it is advantageous for protecting the contactplanes as Well as to insure their reliable mutual engagement if as theinvention furthermore provides, a rotatable latch is provided having itsaxis of rotation disposed perpendicularly to the axis of the guide meansand the engagement planes of the rotary latch and of the guide memberhave as their generatrixes lines which are parallel to the axis ofrotation of the rotary latch so that they engage one another along linesor linearly.

If it is desired to construct the rotary latch particularly simply andeconomically, it is possible in accordance with a further object of theinvention to provide the guide means with a partial cylindrical boreadapted to receive a rotatable cylinder having a part serving as rotarylatch extending through the guide means and which is recessed in such amanner that in its operative position it wedges the guide member of thepresser foot in place while in its inoperative position it frees thecross sectional area of the guide means.

In order to simplify the assembly of the device a two legged spring maybe provided having one leg in a groove of a shoulder of the mounting andretaining the rotatable cylinder in its bearing by engaging the samewith its side while its other leg applies pressure in the direction oflocking upon one arm of a double armed release lever which is secured tothe rotary cylinder and which by' abutting the shoulder at the same timelimits the angular displacement or rotation of the rotary cylinder inboth directions. Thus the spring serves also simultaneously as thefastening element for the rotary latch.

Further details and objects of the invention will become apparent fromthe following specification with reference to the accompanying drawingswhich show two embodiments of the invention and in which:

Fig. 1 is a perspective view of the presser foot secured to the presserbar,

Fig. 2 is an exploded view of the parts of the embodiment in accordancewith Fig. 1,

Figs. 3 to 5 illustrate subsequent positions of the guide member whilebeing inserted into the mounting which is illustrated in a cross sectiontaken along the axis of the guiding means,

Fig. 6 is an illustration similar to Figs. 3 to 5 with the guide memberunlatched,

Fig. 7 is a greatly enlarged view of a section of Fig. 5;,

Fig. 8 illustrates a second embodiment of the mounting; means partly insection along the axis of the guiding means with the guide memberinserted half way, and

Fig. 9 is a view of the embodiment similar to Fig. 81

V with the guide member in latched position.

In the embodiment in accordance with Figs. 1 to 7 a support member 3 issecured to the lower end of thepresser bar 1 by means of a screw 2 theconstruction of which can best be seen in Fig. 2.

The support member 3 is provided with two cylindrical bores 4 and 5which partly intersect one another. The bore 4 connects with a slot 6defined by vertical planes and which is open at the bottom. The bore 5is adapted to receive a rotatable cylinder 7 having a portion 8 whichextends through the bore 4 and which is recessed as illustratedparticularly in Figs. 2 and 7.

A double armed release lever 9 and a retaining pin 10 are securelyfastened to the rotatable cylinder 7. The pin retains a two leggedspring 11 one leg 12 of which rests in a groove 13 against a shoulder 14of the support member 3. The other leg 15 presses against the arm 16 ofthe release lever 9 tending to rotate the same together with the rotarycylinder 7 in counter-clockwise direction. The angular movement of therotatable cylinder 7 is limited in both directions by the release lever9 abutting the shoulder 14. The spring 11 by laterally engagingrotatable cylinder 7 causes the same to be retained in the bore 5.

The cylindrical bore 4 and the slot 6 form in combination a cylindricalguide slot, which prevents rotation and extends inthe direction ofsewing, for a cylindrical guide member 19 provided on the shank 17 ofthe presser foot 18. This guide member 19 is slidingly received from therear in the bore 4 while the vertical side planes 20 of the shank 17 areguided by the walls of slot 6. A collar 21 which enters a recess 22 inthe bore 4 constitutes an abutment limiting the inward movement of theguide member 19. The guide member is also provided with a notch 23 thesurface of which is defined by straight lines extending parallel to andin the direction of the axis of the rotatable cylinder 7.

The mounting of the presser foot 18 is accomplished by first sliding theguide member 19 upon a plane 224 of portion 8 of the rotatable cylinder(Fig. 3) and rotating the same against the action of spring 11 (-Fig. 4)until portion 8 engages the latching position of guide member 19 shownin Fig. 5.

To remove the presser foot :18 the release lever 9 is rotated clockwiseso that the part 8 assumes the position.

shown in Fig. 6. The guide member 19 can now be readily withdrawn fromthe bore 4.

The latching position of the guide member 19 as shown in Fig. 5 is againillustrated in Fig. 7 where it is considerably enlarged. Here Gdesignates the line of contact of member 8 with the guide member 19.Said straight line G extends in that location perpendicularly to theplane of Fig. 7 of the drawing. The contact plane is indicated at T andN is the vertical plane or normal for the contact plane T through thecontact line designated G, while the axis of rotation of rotatablecylinder 7 is indicated at A, the plane passing through the contact lineG and through axis of rotation A is designated E, while on representsthe angle enclosed by the planes E and N. If the angle a is smaller thana predetermined limiting or critical angle, the self-locking becomesoperative. The limiting angle is computed in a known manner inaccordance with the equation tan a= u, where p, is the coefficient offriction of the contact surfaces at the location designated G in thedrawing.

Due to the wedge effect and as a result of the spring biasing of thelatching, the contact location, even if there is some tolerance betweenthe guide member 19 and the bore 4, i.e. with a loose fit, assumes theposition of greatest distance from the axis of the rotary latch. As aresult any load can only eflect a shortening of the distance between thepoint of contact and the axis of rotation. As.

a result of the pressure thus caused at the contact location, theself-locking becomes effective, i.e., the parts no longer can slide oneupon the other so that any shortening of the distance between thecontact location and the axis of rotation is not possible. The load isabsorbed by the bearing of the rotatable latch and the connection iscompletely rigid in spite of a freely sliding fit.

Figs. 8 and 9 illustrate a second embodiment of the invention.

In this embodiment a support member 10 3 is secured to the presser bar 1by means of a screw 2. The support 1113 is provided with a vertical slot106 which is open at the bottom. The slot 106 extends to a positionabove a cylindrical bore 104- disposed in the direction of sewing and islocated in a plane which passes through the axis of the bore 164. Thepart of slot 106 which is located below the bore 104 serves for guidingthe shank 117 of the presser foot.

The slot 106 is provided at one end with a fixed abutment 12-2 which isengaged by an edge 121 of the shank 117 of the presser foot. Theabutment 122 furthermore serves for the support of a two legged spring111. The latter is accommodated in the portion of the slot 106 above thebore 104 and is secured in its position by a pin 11%. In the upper partof slot 106 a double armed latch lever 1th: is mounted for rotationabout an axis 107. A cylindrical guide member 1-19 is provided on theshank 117 of the presser foot which member is provided with acylindrical recess 123 extending transversely of its axis.

As the guide member 119 is inserted (Fig. 8) it engages a leg 115 ofspring 111 and presses the same rearwardly. The spring 111 is therebytensioned and in turn presses with its other leg 112 against the latchlever 108 which drops into the recess 103 when the presser foot is inposition (Fig. 9).

The cylindrical axis of the recess 123 in this connection is disposedsomewhat above the plane through the axis 1d? and point of contact ofthe latch lever 108 and guide member 119 but still analagous to theconditions in accordance with Fig. 7 so that the device operates in aself-locking manner.

If the presser foot in accordance with Fig. 9 is mounted the leg 115 ofspring 111 presses against the guide member 1119 in the direction ofdisengagement. Pressing down on the rearward end 109 of the latch lever108 causes the guide member 119 to be ejected.

As already mentioned in connection with the first embodiment the guidingarrangement can be very loosely fitted. The force of the spring is thenreadily sufficient to completely eject the presser foot.

Having now described our invention with reference to the embodimentsillustrated in the drawings we do not wish to be limited thereto, butwhat we desire to protect by Letters Patent is set forth in the appendedclaims.

We claim: a

1. Means for releasably securing a presser foot to the presser bar of asewing machine, said means comprising, in combination, a support memberadapted to be secured to the presser bar of the machine, and a shanksupporting a presser foot at the lower end thereof and extending intosaid support member; said support member defining a generallyhorizontally disposed cylindrical bore and having a pair of jaws at itslower end defining a slot extending longitudinally of the cylindricalwalls of said bore, and said shank having a guide member at its upperend adapted to be slidingly received in said bore and having an abutmentsurface at one end for contacting said support member adjacent one endof said bore in the mounted position of said presser foot in lockedcondition, and said guide member having a recess extending substantiallycentrally and transversely thereof and presenting a latch surface, andself-locking latch means comprising a lever extending longitudinally ofsaid support member and hav ing a latch portion adapted to engage saidrecess and spring means extending endwise of said lever and biasingsaid'lever and said latch portion into latched position, said leverbeing pivotally mounted and said latch portion engaging said latchsurface along a line in a plane having a. normal disposed at an anglewith respect to the plane extending through the pivot axis of said latchportion and said line, the tangent of said angle being smaller than thecoeflicient of friction of the materials engaging in the area proximatesaid line.

2. Means for releasably securing a presser foot to the presser bar of asewing machine, said means comprising, in combination, a support memberadapted to be secured to the presser bar of the machine, and a shanksupporting a presser foot at the lower end thereof and extending intosaid support member; said support member defining a generallyhorizontally disposed cylindrical bore and having a pair of jaws at itslower end defining a slot extending longitudinally of the cylindricalwalls of said bore, and said shank having a guide. member at its upperend adapted to be slidingly received in said bore and having an abutmentsurface at one end for contacting said support member adjacent one endof said bore in the mounted position of said presser foot in lockedcondition, and said guide member having a recess extending substantiallycentrally and transversely thereof and presenting a latch surface, andself-locking latch means comprising a lever extending longitudinally ofsaid support member and having a latch portion adapted to engage saidrecess and spring means extending endwise of said lever and biasing saidlever and said latch portion into latched position, said lever beingpivotally mounted and said latch portion engaging said latch surfacealong a line in a plane having a normal disposed at an angle withrespect to the plane extending through the pivot axis of said latchportion and said line, the tangent of said angle being smaller than thecoefiicient of friction of the materials engaging in the area proximatesaid line and the pivot axis of said latch portion extendingtransversely of the axis of said guide member.

3. Means for releasably securing a presser foot to the presser bar of asewing machine, said meaus comprising, in combination, a support memberadapted to be secured to the presser bar of the machine, and a shanksupporting a presser foot at the lower end thereof and extending intosaid support member; said support member defining a generallyhorizontally disposed cylindrical bore and having a pair of jaws at itslower end defininga slot extending longitudinally of the cylindricalwalls of said bore, and said shank having a guide member at its upperend adapted to be slidingly received in said bore and having an abutmentsurface at one end for contacting said support member adjacent one endof said bore in the mounted position of said presser foot in lockedcondition, and said guide member having a recess extending substantiallycentrally and transversely thereof and presenting a latch surface, andself-locking latch means comprising a lever extending longitudinally ofsaid support member and having a latch portion adapted to engage saidrecess and spring means extending endwise of said lever and biasing saidlever and said latch portion into latched position, said lever beingpivotally mounted and said latch portion engaging said latch surfacealong a line in a plane having a normal disposed at an angle withrespect to the plane extending through the pivot axis of said latchportion and said line, the tangent of said angle being smaller than thecoeflicient of friction of the materials enaging in the area proximatesaid line, and the areas of said latch surface and of said latch portionalong the line of contact being contact planes having the same angle ofinclination.

4. Means for releasably securing a presser foot to the presser bar of asewing machine, said means comprising, in combination, a support memberadapted to be secured to the presser bar of the machine, and a shanksupporting a presser foot at the lower end thereof and extending intosaid support member; said support member defining a generallyhorizontally disposed cylindrical bore and having a pair of jaws at itslower end defining a slot extending longitudinally of the cylindricalwalls of said bore, and said shank having a guide member at its upperend adapted to be slidingly received in said bore and having an abutmentsurface at one end for contacting said support member adjacent one endof said bore in the mounted position of said presser foot in lockedcondition, and said guide member having a recess extending substantiallycentrally and transversely thereof and presenting a latch surface, andself-locking latch means comprising a lever extending longitudinally ofsaid support member and having a latch portion adapted to engage saidrecess and spring means extending endwise of said lever and biasing saidlever and said latch portion into latched position, said lever beingpivotally mounted and said latch portion engaging said latch surfacealong a line in a plane having a normal disposed at an angle withrespect to the plane extending through the pivot axis of said latchportion and said line, the tangent of said angle being smaller than thecoefficient of friction of the materials engaging in the area proximatesaid line, said support member having a transverse bore intersecting aportion of said slot and said latch portion defining a substantiallycylindrical latch member in said bore having an outwardly extending endportion secured to said lever and a pin supporting said spring means andasid spring means having one leg in engagement with said lever andanother leg biased against said support member.

5. Means for releasably securing a presser foot to the presser bar of asewing machine, said means comprising, in combination, a support memberadapted to be secured to the presser bar of the machine, and a shanksupporting a presser foot at the lower end thereof and extending intosaid support member; said support member defining a generallyhorizontally disposed cylindrical bore and having a pair of jaws at itslower end defining a slot extending longitudinally of the cylindricalwalls of said bore, and said shank having a guide member at its upperend adapted to be slidingly received in said bore and having an abutmentsurface at one end for contacting said support member adjacent one endof said bore in the mounted position of said presser foot in lockedcondition, and said guide member having a recess extending substantiallycentrally and transversely thereof and presenting a latch surface, andself-locking latch means comprising a lever extending longitudinally ofsaid support member and having a latch portion adapted to engage saidrecess and spring means extending endwise of said lever and biasing saidlever and said latch portion into latched position, said lever beingpivotally mounted and said latch portion engaging said latch surfacealong a line in a plane having a normal disposed at an angle withrespect to the plane extending through the pivot axis of said latchportion and said line, the tangent of said angle being smaller than thecoefiicient of friction of the materials engaging in the area proximatesaid line, said bore and said slot being defined partly by a circularcylinder and partly by even planes on said jaws extending outwardly ofsaid cylinder and said guide member having a cylindrical portion adaptedto enter said bore and comprising vertical side planes on said shankadapted to engage said even planes of said guide slot.

6. Means for releasably securing a presser foot to the presser bar of asewing machine, said means comprising, in combination, a support memberadapted to be secured to the presser bar of the machine, and a shanksupporting a presser foot at the lower end thereof and extending intosaid support member; said support member defining a generallyhorizontally disposed cylindrical ,bore and having a pair of jaws at itslower end defining a slot extending longitudinally of the cylindricalwalls of said bore, and said shank having a guide member at its upperend adapted to be slidably received in said bore and having an abutmentsurface at one end for contacting said support member adjacent one endof said bore in the mounted position of said presser foot in lockedcondition, and said guide member having a recess extending substantiallycentrally and transversely thereof and presenting a latch surface, andself-locking latch means comprising a lever extending longitudinally ofsaid support member and having a latch portion adapted to engage saidrecess and spring means extending endwise of said lever and biasing saidlever and said latch portion into latched position, said lever beingpivotally mounted and said latch portion engaging said latch surfacealong a line in a plane having a normal disposed at an angle withrespect to the plane extending through the pivot axis of said latchportion and said line, the tangent of said angle being smaller than thecoefficient of friction of the materials engaging in the area proximatesaid line, said support member having a transverse bore intersecting aportion of said slot and said latch portion defining a substantiallycylindrical latch member in said bore having an outwardly extending endportion secured to said lever and a pin supporting said spring means,and said spring means having one leg in engagement with said lever andanother leg biased against said support member, and said spring beingadapted to eject said guide member from said slot upon release of saidguide member by said latch portion and outward movement of said guidemember by engagement of said latch portion with the forward end of saidguide member.

7. Means for releasably securing a presser foot to the presser bar of asewing machine, said means comprising, in combination, a support memberadapted to be secured to the presser bar of the machine, and a shanksupporting a presser foot at the lower end thereof and extending intosaid support member; said support member defining a generallyhorizontally disposed cylindrical bore and having a pair of jaws at itslower end defining a slot extending longitudinally of the cylindricalwalls of said bore, and said shank having a guide member at its upperend adapted to be slidingly received in said bore and having an abutmentsurface at one end for contacting said support member adjacent one endof said bore in the mounted position of said presser foot in lockedcondition, and said guide member having a recess extending substantiallycentrally and transversely thereof and presenting a latch surface, andself-locking latch means comprising a lever extending longitudinally ofsaid support member and having a latch portion adapted to engage saidrecess and spring means extending endwise of said lever and biasing saidlever and said latch portion into latched position, said lever beingpivotally mounted and said latch. portion enga sa d. latch surface. a na line in. a pl n h v a normal dispose t an an le ith respect to theplane extending through the pivot axis of said latch portion and saidline, the tangent of said angle being smaller than the coeificient offriction oi the materials engaging in the area proximate said line, saidresilient means comprising a spring having a pair of legs biased towardeach other and said bore connecting with an upwardly extending groovehaving parallel sides adapted to receive said lever and one leg of saidspring, said one leg of said spring being in engagement with one end ofsaid lever defining said latch portion and said latch portion being inengagement with said latch sure face, and the other leg of said springbeing disposed Refe en es Cited the file of th s p en UNITED STATESPATENTS 78,652 Craig June 9, 1868 FOREIGN PATENTS 1,096,141 France o-r-- Dec. 29, 1954

